RESUMO
The recent elegant study by Y. Yuan and colleagues examined functional relationships between the lysosomal two-pore channels 2 (TPC2) and IP3 receptors (IP3Rs) located in the endoplasmic reticulum [1]. The findings of this study suggest functional coupling of these channels and receptors. The study also describes interesting novel phenomena, which may indicate an additional coupling mechanism.
Assuntos
Sinalização do Cálcio , Canais de Dois Poros , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Retículo Endoplasmático/metabolismo , Lisossomos/metabolismo , Cálcio/metabolismo , NADP/metabolismoRESUMO
Recent studies have highlighted the importance of autophagy and particularly non-canonical autophagy in the development and progression of acute pancreatitis (a frequent disease with considerable morbidity and significant mortality). An important early event in the development of acute pancreatitis is the intrapancreatic activation of trypsinogen, (i.e., formation of trypsin) leading to the autodigestion of the organ. Another prominent phenomenon associated with the initiation of this disease is vacuolisation and specifically the formation of giant endocytic vacuoles in pancreatic acinar cells. These organelles develop in acinar cells exposed to several inducers of acute pancreatitis (including taurolithocholic acid and high concentrations of secretagogues cholecystokinin and acetylcholine). Notably, early trypsinogen activation occurs in the endocytic vacuoles. These trypsinogen-activating organelles undergo activation, long-distance trafficking, and non-canonical autophagy. In this review, we will discuss the role of autophagy in acute pancreatitis and particularly focus on the recently discovered LAP-like non-canonical autophagy (LNCA) of endocytic vacuoles.
Assuntos
Pancreatite , Tripsinogênio , Doença Aguda , Autofagia , Humanos , VacúolosRESUMO
Salivary secretion is important for digestion and paramount for oral health. Both exocytotic secretion of proteins (including salivary amylase and mucins) and fluid secretion contribute to the formation of saliva. A recent study by T. Takano and colleagues [1] has revealed interesting patterns of Ca2+ responses with implications for important modifications to the established model of fluid secretion.
Assuntos
Células Acinares , Cálcio , Saliva , Glândulas Salivares , Transdução de SinaisRESUMO
Acute pancreatitis (AP) is a severe and potentially fatal disease caused predominantly by alcohol excess and gallstones, which lacks a specific therapy. The role of Receptor-Interacting Protein Kinase 1 (RIPK1), a key component of programmed necrosis (Necroptosis), is unclear in AP. We assessed the effects of RIPK1 inhibitor Necrostatin-1 (Nec-1) and RIPK1 modification (RIPK1K45A: kinase dead) in bile acid (TLCS-AP), alcoholic (FAEE-AP) and caerulein hyperstimulation (CER-AP) mouse models. Involvement of collateral Nec-1 target indoleamine 2,3-dioxygenase (IDO) was probed with the inhibitor Epacadostat (EPA). Effects of Nec-1 and RIPK1K45A were also compared on pancreatic acinar cell (PAC) fate in vitro and underlying mechanisms explored. Nec-1 markedly ameliorated histological and biochemical changes in all models. However, these were only partially reduced or unchanged in RIPK1K45A mice. Inhibition of IDO with EPA was protective in TLCS-AP. Both Nec-1 and RIPK1K45A modification inhibited TLCS- and FAEE-induced PAC necrosis in vitro. Nec-1 did not affect TLCS-induced Ca2+ entry in PACs, however, it inhibited an associated ROS elevation. The results demonstrate protective actions of Nec-1 in multiple models. However, RIPK1-dependent necroptosis only partially contributed to beneficial effects, and actions on targets such as IDO are likely to be important.
Assuntos
Imidazóis/uso terapêutico , Indóis/uso terapêutico , Pancreatite/tratamento farmacológico , Pancreatite/enzimologia , Substâncias Protetoras/uso terapêutico , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Células Acinares/metabolismo , Álcoois , Animais , Ácidos e Sais Biliares , Cálcio/metabolismo , Ceruletídeo , Imidazóis/farmacologia , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Indóis/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Pâncreas/patologia , Pancreatite/induzido quimicamente , Substâncias Protetoras/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/antagonistas & inibidoresRESUMO
Acute pancreatitis is a frequent disease that lacks specific drug treatment. Unravelling the molecular mechanisms of acute pancreatitis is essential for the development of new therapeutics. Several inducers of acute pancreatitis trigger sustained Ca2+ increases in the cytosol and mitochondria of pancreatic acinar cells. The mitochondrial calcium uniporter (MCU) mediates mitochondrial Ca2+ uptake that regulates bioenergetics and plays an important role in cell survival, damage and death. Aberrant Ca2+ signaling and mitochondrial damage in pancreatic acinar cells have been implicated in the initiation of acute pancreatitis. The primary aim of this study was to assess the involvement of the MCU in experimental acute pancreatitis. We found that pancreatic acinar cells from MCU-/- mice display dramatically reduced mitochondrial Ca2+ uptake. This is consistent with the drastic changes of stimulus-metabolism coupling, manifested by the reduction of mitochondrial NADH/FAD+ responses to cholecystokinin and in the decrease of cholecystokinin-stimulated oxygen consumption. However, in three experimental models of acute pancreatitis (induced by caerulein, taurolithocholic acid 3-sulfate or palmitoleic acid plus ethanol), MCU knockout failed to reduce the biochemical and histological changes characterizing the severity of local and systemic damage. A possible explanation of this surprising finding is the redundancy of damaging mechanisms activated by the inducers of acute pancreatitis.
Assuntos
Células Acinares/metabolismo , Canais de Cálcio/metabolismo , Pâncreas/patologia , Pancreatite/metabolismo , Pancreatite/patologia , Índice de Gravidade de Doença , Animais , Cálcio/metabolismo , Sinalização do Cálcio , Citosol/metabolismo , Modelos Animais de Doenças , Flavina-Adenina Dinucleotídeo/metabolismo , Camundongos Knockout , Mitocôndrias/metabolismo , NAD/metabolismoRESUMO
Activation of trypsinogen (formation of trypsin) inside the pancreas is an early pathological event in the development of acute pancreatitis. In our previous studies we identified the activation of trypsinogen within endocytic vacuoles (EVs), cellular organelles that appear in pancreatic acinar cells treated with the inducers of acute pancreatitis. EVs are formed as a result of aberrant compound exocytosis and subsequent internalization of post-exocytic structures. These organelles can be up to 12 µm in diameter and can be actinated (i.e. coated with F-actin). Notably, EVs can undergo intracellular rupture and fusion with the plasma membrane, providing trypsin with access to cytoplasmic and extracellular targets. Unraveling the mechanisms involved in cellular processing of EVs is an interesting cell biological challenge with potential benefits for understanding acute pancreatitis. In this study we have investigated autophagy of EVs and discovered that it involves a non-canonical LC3-conjugation mechanism, reminiscent in its properties to LC3-associated phagocytosis (LAP); in both processes LC3 was recruited to single, outer organellar membranes. Trypsinogen activation peptide was observed in approximately 55% of LC3-coated EVs indicating the relevance of the described process to the early cellular events of acute pancreatitis. We also investigated relationships between actination and non-canonical autophagy of EVs and concluded that these processes represent sequential steps in the evolution of EVs. Our study expands the known roles of LAP and indicates that, in addition to its well-established functions in phagocytosis and macropinocytosis, LAP is also involved in the processing of post-exocytic organelles in exocrine secretory cells. ABBREVIATIONS: AP: acute pancreatitis; CCK: cholecystokinin; CLEM: correlative light and electron microscopy; DPI: diphenyleneiodonium; EV: endocytic vacuole; LAP: LC3-associate phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; PACs: pancreatic acinar cells; PFA: paraformaldehyde; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; Res: resveratrol; TAP: trypsinogen activation peptide; TEM: transmission electron microscopy; TLC-S: taurolithocholic acid 3-sulfate; TRD: Dextran Texas Red 3000 MW Neutral; ZGs: zymogen granules.
Assuntos
Células Acinares/metabolismo , Autofagia , Endocitose , Proteínas Associadas aos Microtúbulos/metabolismo , Pâncreas/citologia , Fagocitose , Vacúolos/metabolismo , Sal Dissódico do Ácido 1,2-Di-Hidroxibenzeno-3,5 Dissulfônico/farmacologia , Células Acinares/efeitos dos fármacos , Células Acinares/ultraestrutura , Actinas/metabolismo , Animais , Autofagia/efeitos dos fármacos , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/antagonistas & inibidores , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/metabolismo , Proteínas Relacionadas à Autofagia/química , Proteínas Relacionadas à Autofagia/metabolismo , Cloroquina/farmacologia , Colecistocinina/farmacologia , Camundongos Endogâmicos C57BL , Oniocompostos/farmacologia , Fagocitose/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Domínios Proteicos , Inibidores de Proteínas Quinases/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Resveratrol/farmacologia , Ácido Taurolitocólico/análogos & derivados , Tripsinogênio/metabolismo , ATPases Vacuolares Próton-Translocadoras/antagonistas & inibidores , ATPases Vacuolares Próton-Translocadoras/metabolismo , Vacúolos/efeitos dos fármacosRESUMO
Acute pancreatitis (AP) is a debilitating, sometimes fatal disease, marked by local injury and systemic inflammation. Mitochondrial dysfunction is a central feature of pancreatic damage in AP, however, its involvement in circulating blood cell subtypes is unknown. This study compared mitochondrial bioenergetics in circulating leukocytes from AP patients and healthy volunteers: 15 patients with mild to severe AP were compared to 10 healthy controls. Monocytes, lymphocytes and neutrophils were isolated using magnetic activated cell sorting and mitochondrial bioenergetics profiles of the cell populations determined using a Seahorse XF24 flux analyser. Rates of oxygen consumption (OCR) and extracellular acidification (ECAR) under conditions of electron transport chain (ETC) inhibition ("stress" test) informed respiratory and glycolytic parameters, respectively. Phorbol ester stimulation was used to trigger the oxidative burst. Basal OCR in all blood cell subtypes was similar in AP patients and controls. However, maximal respiration and spare respiratory capacity of AP patient lymphocytes were decreased, indicating impairment of functional capacity. A diminished oxidative burst occurred in neutrophils from AP patients, compared to controls, whereas this was enhanced in both monocytes and lymphocytes. The data demonstrate important early alterations of bioenergetics in blood cell sub-populations from AP patients, which imply functional alterations linked to clinical disease progression.
RESUMO
Mitochondrial dysfunction is a core feature of acute pancreatitis, a severe disease in which oxidative stress is elevated. Mitochondrial targeting of antioxidants is a potential therapeutic strategy for this and other diseases, although thus far mixed results have been reported. We investigated the effects of mitochondrial targeting with the antioxidant MitoQ on pancreatic acinar cell bioenergetics, adenosine triphosphate (ATP) production and cell fate, in comparison with the non-antioxidant control decyltriphenylphosphonium bromide (DecylTPP) and general antioxidant N-acetylcysteine (NAC). MitoQ (µM range) and NAC (mM range) caused sustained elevations of basal respiration and the inhibition of spare respiratory capacity, which was attributable to an antioxidant action since these effects were minimal with DecylTPP. Although MitoQ but not DecylTPP decreased cellular NADH levels, mitochondrial ATP turnover capacity and cellular ATP concentrations were markedly reduced by both MitoQ and DecylTPP, indicating a non-specific effect of mitochondrial targeting. All three compounds were associated with a compensatory elevation of glycolysis and concentration-dependent increases in acinar cell apoptosis and necrosis. These data suggest that reactive oxygen species (ROS) contribute a significant negative feedback control of basal cellular metabolism. Mitochondrial targeting using positively charged molecules that insert into the inner mitochondrial member appears to be deleterious in pancreatic acinar cells, as does an antioxidant strategy for the treatment of acute pancreatitis.
Assuntos
Células Acinares/metabolismo , Antioxidantes/metabolismo , Linhagem da Célula , Metabolismo Energético , Mitocôndrias/metabolismo , Pâncreas/citologia , Acetilcisteína/farmacologia , Células Acinares/efeitos dos fármacos , Trifosfato de Adenosina/biossíntese , Animais , Morte Celular/efeitos dos fármacos , Linhagem da Célula/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Flavina-Adenina Dinucleotídeo/metabolismo , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , NAD/metabolismo , Oniocompostos/farmacologia , Compostos Organofosforados/farmacologia , Oxirredução , Ubiquinona/análogos & derivados , Ubiquinona/farmacologiaRESUMO
Histones are positively charged nuclear proteins that facilitate packaging of DNA into nucleosomes common to all eukaryotic cells. Upon cell injury or cell signalling processes, histones are released passively through cell necrosis or actively from immune cells as part of extracellular traps. Extracellular histones function as microbicidal proteins and are pro-thrombotic, limiting spread of infection or isolating areas of injury to allow for immune cell infiltration, clearance of infection and initiation of tissue regeneration and repair. Histone toxicity, however, is not specific to microbes and contributes to tissue and end-organ injury, which in cases of systemic inflammation may lead to organ failure and death. This review details the processes of histones release in acute inflammation, the mechanisms of histone-related tissue toxicity and current and future strategies for therapy targeting histones in acute inflammatory diseases.
Assuntos
Alarminas/imunologia , Doenças Transmissíveis/imunologia , Histonas/imunologia , Necrose/imunologia , Receptores de Reconhecimento de Padrão/imunologia , Trombose/imunologia , Alarminas/sangue , Alarminas/genética , Anti-Inflamatórios/uso terapêutico , Fatores de Coagulação Sanguínea/genética , Fatores de Coagulação Sanguínea/imunologia , Fatores Quimiotáticos/sangue , Fatores Quimiotáticos/genética , Fatores Quimiotáticos/imunologia , Quimiotaxia/imunologia , Doenças Transmissíveis/genética , Doenças Transmissíveis/patologia , Doenças Transmissíveis/terapia , Espaço Extracelular/química , Espaço Extracelular/imunologia , Armadilhas Extracelulares/química , Armadilhas Extracelulares/imunologia , Regulação da Expressão Gênica , Histonas/sangue , Histonas/genética , Humanos , Imunidade Inata , Inflamação , Necrose/genética , Necrose/patologia , Necrose/terapia , Neutrófilos , Receptores de Reconhecimento de Padrão/genética , Transdução de Sinais , Trombose/genética , Trombose/patologia , Trombose/terapiaRESUMO
Cellular organelles form multiple junctional complexes with one another and the emerging research area dealing with such structures and their functions is undergoing explosive growth. A new research journal named "Contact" has been recently established to facilitate the development of this research field. The current consensus is to define an organellar junction by the maximal distance between the participating organelles; and the gap of 30 nm or less is considered appropriate for classifying such structures as junctions or membrane contact sites. Ideally, the organellar junction should have a functional significance, i.e. facilitate transfer of calcium, sterols, phospholipids, iron and possibly other substances between the organelles (Carrasco and Meyer in Annu Rev Biochem 80:973-1000, 2011; Csordas et al. in Trends Cell Biol 28:523-540, 2018; Phillips and Voeltz in Nat Rev Mol Cell Biol 17:69-82, 2016; Prinz in J Cell Biol 205:759-769, 2014). It is also important to note that the junction is not just a result of a random organelle collision but have active and specific formation, stabilisation and disassembly mechanisms. The nature of these mechanisms and their role in physiology/pathophysiology are the main focus of an emerging research field. In this review, we will briefly describe junctional complexes formed by cellular organelles and then focus on the junctional complexes that are formed by mitochondria with other organelles and the role of these complexes in regulating Ca2+ signalling.
Assuntos
Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Mitocôndrias/metabolismo , Mitocôndrias/fisiologia , Animais , HumanosRESUMO
F1F0-ATP synthase inhibitory factor 1 (IF1) inhibits the reverse mode of F1F0-ATP synthase, and therefore protects cellular ATP content at the expense of accelerated loss of mitochondrial membrane potential (ΔΨm). There is considerable variability in IF1 expression and its influence on bioenergetics between different cell types. High levels of IF1 in a number of cancers have been linked to increased glycolysis, resistance to cell death, increased migration and proliferation. However, neither the expression nor role of IF1 in the normal pancreas or in pancreatic cancer has been characterized. In this study, we found that pancreatic ductal adenocarcinoma (PDAC) patients express higher levels of IF1 in cancerous cells than in pancreatic acinar cells (PACs). PDAC cell lines have a higher IF1 content and IF1/ATP synthase ratio than PACs. The observed differences are consistent with the ability of the respective cell types to maintain ΔΨm and ATP levels in conditions of chemical hypoxia. Acinar cells and PDAC cells preferentially express different IF1 isoforms. Both knockdown and knockout of IF1 in the PANC-1 pancreatic cancer cell line modified cellular bioenergetics and decreased migration, invasion and proliferation suggesting the putative importance of IF1 for PDAC growth and metastasis.
RESUMO
KEY POINTS: Giant trypsin-containing endocytic vacuoles are formed in pancreatic acinar cells stimulated with inducers of acute pancreatitis. F-actin envelops endocytic vacuoles and regulates their properties. Endocytic vacuoles can rupture and release their content into the cytosol of acinar cells. Endocytic vacuoles can fuse with the plasma membrane of acinar cells and exocytose their content. ABSTRACT: Intrapancreatic activation of trypsinogen is an early event in and hallmark of the development of acute pancreatitis. Endocytic vacuoles, which form by disconnection and transport of large post-exocytic structures, are the only resolvable sites of the trypsin activity in live pancreatic acinar cells. In the present study, we characterized the dynamics of endocytic vacuole formation induced by physiological and pathophysiological stimuli and visualized a prominent actin coat that completely or partially surrounded endocytic vacuoles. An inducer of acute pancreatitis taurolithocholic acid 3-sulphate and supramaximal concentrations of cholecystokinin triggered the formation of giant (more than 2.5 µm in diameter) endocytic vacuoles. We discovered and characterized the intracellular rupture of endocytic vacuoles and the fusion of endocytic vacuoles with basal and apical regions of the plasma membrane. Experiments with specific protease inhibitors suggest that the rupture of endocytic vacuoles is probably not induced by trypsin or cathepsin B. Perivacuolar filamentous actin (observed on the surface of â¼30% of endocytic vacuoles) may play a stabilizing role by preventing rupture of the vacuoles and fusion of the vacuoles with the plasma membrane. The rupture and fusion of endocytic vacuoles allow trypsin to escape the confinement of a membrane-limited organelle, gain access to intracellular and extracellular targets, and initiate autodigestion of the pancreas, comprising a crucial pathophysiological event.
Assuntos
Células Acinares/patologia , Exocitose , Pâncreas Exócrino/patologia , Pancreatite/patologia , Vesículas Transportadoras/patologia , Vacúolos/fisiologia , Células Acinares/metabolismo , Doença Aguda , Animais , Masculino , Camundongos , Pâncreas Exócrino/metabolismo , Pancreatite/etiologia , Vesículas Transportadoras/metabolismoRESUMO
Mitochondrial dysfunction lies at the core of acute pancreatitis (AP). Diverse AP stimuli induce Ca2+-dependent formation of the mitochondrial permeability transition pore (MPTP), a solute channel modulated by cyclophilin D (CypD), the formation of which causes ATP depletion and necrosis. Oxidative stress reportedly triggers MPTP formation and is elevated in clinical AP, but how reactive oxygen species influence cell death is unclear. Here, we assessed potential MPTP involvement in oxidant-induced effects on pancreatic acinar cell bioenergetics and fate. H2O2 application promoted acinar cell apoptosis at low concentrations (1-10 µm), whereas higher levels (0.5-1 mm) elicited rapid necrosis. H2O2 also decreased the mitochondrial NADH/FAD+ redox ratio and ΔΨm in a concentration-dependent manner (10 µm to 1 mm H2O2), with maximal effects at 500 µm H2O2 H2O2 decreased the basal O2 consumption rate of acinar cells, with no alteration of ATP turnover at <50 µm H2O2 However, higher H2O2 levels (≥50 µm) diminished spare respiratory capacity and ATP turnover, and bioenergetic collapse, ATP depletion, and cell death ensued. Menadione exerted detrimental bioenergetic effects similar to those of H2O2, which were inhibited by the antioxidant N-acetylcysteine. Oxidant-induced bioenergetic changes, loss of ΔΨm, and cell death were not ameliorated by genetic deletion of CypD or by its acute inhibition with cyclosporine A. These results indicate that oxidative stress alters mitochondrial bioenergetics and modifies pancreatic acinar cell death. A shift from apoptosis to necrosis appears to be associated with decreased mitochondrial spare respiratory capacity and ATP production, effects that are independent of CypD-sensitive MPTP formation.
Assuntos
Apoptose , Ciclofilinas/fisiologia , Mitocôndrias/fisiologia , Proteínas de Transporte da Membrana Mitocondrial/fisiologia , Necrose , Estresse Oxidativo , Pâncreas/patologia , Células Acinares/metabolismo , Células Acinares/patologia , Trifosfato de Adenosina/metabolismo , Animais , Cálcio/metabolismo , Células Cultivadas , Peptidil-Prolil Isomerase F , Metabolismo Energético , Potencial da Membrana Mitocondrial , Camundongos Endogâmicos C57BL , Camundongos Knockout , Poro de Transição de Permeabilidade Mitocondrial , Pâncreas/metabolismo , Espécies Reativas de Oxigênio/metabolismoRESUMO
OBJECTIVES: Mitochondrial permeability transition pore inhibition is a promising approach to treat acute pancreatitis (AP). We sought to determine (i) the effects of the mitochondrial permeability transition pore inhibitor 3,5-seco-4-nor-cholestan-5-one oxime-3-ol (TRO40303) on murine and human pancreatic acinar cell (PAC) injury induced by fatty acid ethyl esters (FAEEs) or taurolithocholic acid-3-sulfate and (ii) TRO40303 pharmacokinetics and efficacy in experimental alcoholic AP (FAEE-AP). METHODS: Changes in mitochondrial membrane potential (Δψm), cytosolic Ca ([Ca]c), and cell fate were examined in freshly isolated murine or human PACs by confocal microscopy. TRO40303 pharmacokinetics were assessed in cerulein-induced AP and therapeutic efficacy in FAEE-AP induced with palmitoleic acid and ethanol. Severity of AP was assessed by standard biomarkers and blinded histopathology. RESULTS: TRO40303 prevented loss of Δψm and necrosis induced by 100 µM palmitoleic acid ethyl ester or 500 µM taurolithocholic acid-3-sulfate in murine and human PACs. Pharmacokinetic analysis found TRO40303 accumulated in the pancreas. A single dose of 3 mg/kg TRO40303 significantly reduced serum amylase (P = 0.043), pancreatic trypsin (P = 0.018), and histopathology scores (P = 0.0058) in FAEE-AP. CONCLUSIONS: TRO40303 protects mitochondria and prevents necrotic cell death pathway activation in murine and human PACs, ameliorates the severity of FAEE-AP, and is a candidate drug for human AP.
Assuntos
Ésteres/farmacologia , Ácidos Graxos/farmacologia , Mitocôndrias/efeitos dos fármacos , Oximas/farmacologia , Pancreatite Alcoólica/prevenção & controle , Secoesteroides/farmacologia , Células Acinares/efeitos dos fármacos , Células Acinares/metabolismo , Doença Aguda , Animais , Ceruletídeo , Ésteres/metabolismo , Ácidos Graxos/metabolismo , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Necrose/prevenção & controle , Oximas/farmacocinética , Pancreatite/induzido quimicamente , Pancreatite/prevenção & controle , Pancreatite Alcoólica/metabolismo , Pancreatite Alcoólica/patologia , Secoesteroides/farmacocinética , Ácido Taurolitocólico/análogos & derivados , Ácido Taurolitocólico/farmacologiaRESUMO
In the title of this part of the book, the tail is wagging not just in a single dog but multiple dogs; in other words, a single process SOCE (tail) somehow involves a cross talk of (wagging) large and powerful organelle and cellular compartments (dogs). So how is this possible? Is this really necessary? Is the title actually appropriate?SOCE is a rather special process, it allows efficient signaling based on a ubiquitous second messenger (Ca2+) in multiple cell and tissue types, it has specific signaling modality (i.e., some downstream reactions depend specifically on SOCE and not just on global Ca2+ increase), it is vital for the normal functioning of multiple types of cells and tissues, and when misregulated it induces important pathological processes. The reader hopefully agree that such an important "tail" is more appropriate for a kangaroo than for a Chihuahua and that it has awesome wagging capacity.
Assuntos
Canais de Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Sistemas do Segundo Mensageiro/fisiologia , Animais , HumanosRESUMO
The junctions between the endoplasmic reticulum and the plasma membrane are essential platforms for the activation of store-operated Ca2+ influx. These junctions have specific dimensions and are nonuniformly distributed in polarized cells. The mechanisms involved in the formation of the junctions are currently undergoing vigorous investigation, and significant progress was attained in this research area during the last 10 years. Some cell types display stationary junctions, while in other cells, new junctions can form rapidly following cytosolic Ca2+ signals and/or the reduction of the Ca2+ concentration in the lumen of the endoplasmic reticulum; furthermore, in moving cells, junctions can undergo saltatory formation, long distance sliding, and dissolution. The proteins involved in the activation of the Ca2+ influx could be also involved in the formation of the junctions. The architecture, dynamics, and localization of the junctions are important for the regulation of Ca2+ signaling cascades and their downstream events.
Assuntos
Canais de Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Membrana Celular/metabolismo , Retículo Endoplasmático/metabolismo , Junções Intercelulares/metabolismo , Animais , HumanosRESUMO
OBJECTIVES: To evaluate the therapeutic potential of I-BET-762, an inhibitor of the bromodomain and extra-terminal (BET) protein family, in experimental acute pancreatitis (AP). METHODS: AP was induced by retrograde infusion of taurolithocholic acid sulphate into the biliopancreatic duct (TLCS-AP) or 2 intraperitoneal (i.p.) injections of ethanol and palmitoleic acid 1 h apart (FAEE-AP) or 12 hourly i.p. injections of caerulein (CER-AP). In all treatment groups, I-BET-762 (30 mg/kg, i.p.) was administered at the time of disease induction and again 12 h later. AP severity was assessed at 24 h by serum biochemistry, multiple cytokines and histopathology. RESULTS: TLCS-AP, FAEE-AP and CER-AP resulted in characteristic elevations in serum amylase and cytokine levels, increased pancreatic trypsin and myeloperoxidase activity, typical pancreatic histopathological changes and lung injury. Treatment with I-BET-762 significantly reduced biochemical, cytokine and histopathological responses in TLCS-AP and FAEE-AP, but not CER-AP. CONCLUSIONS: These results suggest that in different forms of AP there are significant differences in the epigenetic control of gene transcription contributing to the severity of disease responses. There is therapeutic potential in targeting bromodomains for the treatment of gallstone- and alcohol-related pancreatitis.
Assuntos
Benzodiazepinas/farmacologia , Ácidos e Sais Biliares/toxicidade , Ceruletídeo/toxicidade , Proteínas do Tecido Nervoso/antagonistas & inibidores , Pancreatite/induzido quimicamente , Receptores de Superfície Celular/antagonistas & inibidores , Ácido Taurolitocólico/análogos & derivados , Doença Aguda , Amilases/sangue , Amilases/metabolismo , Animais , Citocinas/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Inflamação/prevenção & controle , Pulmão/enzimologia , Masculino , Camundongos , Pâncreas/enzimologia , Pâncreas/patologia , Pancreatite/terapia , Peroxidase/genética , Peroxidase/metabolismo , Ácido Taurolitocólico/toxicidade , Tripsina/metabolismoRESUMO
OBJECTIVE: Caffeine reduces toxic Ca2+ signals in pancreatic acinar cells via inhibition of inositol 1,4,5-trisphosphate receptor (IP3R)-mediated signalling, but effects of other xanthines have not been evaluated, nor effects of xanthines on experimental acute pancreatitis (AP). We have determined effects of caffeine and its xanthine metabolites on pancreatic acinar IP3R-mediated Ca2+ signalling and experimental AP. DESIGN: Isolated pancreatic acinar cells were exposed to secretagogues, uncaged IP3 or toxins that induce AP and effects of xanthines, non-xanthine phosphodiesterase (PDE) inhibitors and cyclic adenosine monophosphate and cyclic guanosine monophosphate (cAMP/cGMP) determined. The intracellular cytosolic calcium concentration ([Ca2+]C), mitochondrial depolarisation and necrosis were assessed by confocal microscopy. Effects of xanthines were evaluated in caerulein-induced AP (CER-AP), taurolithocholic acid 3-sulfate-induced AP (TLCS-AP) or palmitoleic acid plus ethanol-induced AP (fatty acid ethyl ester AP (FAEE-AP)). Serum xanthines were measured by liquid chromatography-mass spectrometry. RESULTS: Caffeine, dimethylxanthines and non-xanthine PDE inhibitors blocked IP3-mediated Ca2+ oscillations, while monomethylxanthines had little effect. Caffeine and dimethylxanthines inhibited uncaged IP3-induced Ca2+ rises, toxin-induced Ca2+ release, mitochondrial depolarisation and necrotic cell death pathway activation; cAMP/cGMP did not inhibit toxin-induced Ca2+ rises. Caffeine significantly ameliorated CER-AP with most effect at 25â mg/kg (seven injections hourly); paraxanthine or theophylline did not. Caffeine at 25â mg/kg significantly ameliorated TLCS-AP and FAEE-AP. Mean total serum levels of dimethylxanthines and trimethylxanthines peaked at >2â mM with 25â mg/kg caffeine but at <100â µM with 25â mg/kg paraxanthine or theophylline. CONCLUSIONS: Caffeine and its dimethylxanthine metabolites reduced pathological IP3R-mediated pancreatic acinar Ca2+ signals but only caffeine ameliorated experimental AP. Caffeine is a suitable starting point for medicinal chemistry.
Assuntos
Células Acinares/efeitos dos fármacos , Cafeína/farmacologia , Cálcio/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/antagonistas & inibidores , Pâncreas/patologia , Pancreatite/prevenção & controle , Inibidores de Fosfodiesterase/farmacologia , Células Acinares/metabolismo , Animais , Cafeína/uso terapêutico , Morte Celular/efeitos dos fármacos , Células Cultivadas , Ceruletídeo , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Citosol/metabolismo , Etanol , Ácidos Graxos Monoinsaturados , Inositol 1,4,5-Trifosfato/metabolismo , Masculino , Camundongos , Microscopia Confocal , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/fisiologia , Necrose/diagnóstico por imagem , Pancreatite/sangue , Pancreatite/induzido quimicamente , Inibidores de Fosfodiesterase/uso terapêutico , Transdução de Sinais/efeitos dos fármacos , Ácido Taurolitocólico/análogos & derivados , Xantinas/sangue , Xantinas/farmacologiaRESUMO
Mitochondrial Ca(2+) entry is an important process regulating cellular bioenergetics, redox responses, and apoptosis. The study by Vais and colleagues (Vais et al., 2016), recently published in Cell Reports, describes a novel mechanism of modulating Ca(2+) entry that involves mitochondrial matrix Ca(2+).